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Difficulties of the microscopic theory of leakage current through ultra‐thin oxide barriers: point defects
Author(s) -
Fonseca Leonardo R. C.,
Demkov Alexander A.,
Knizhnik Andrey
Publication year - 2003
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200303243
Subject(s) - vacancy defect , materials science , density functional theory , leakage (economics) , crystallographic defect , oxide , band gap , condensed matter physics , molecular physics , crystallography , chemistry , computational chemistry , optoelectronics , physics , metallurgy , macroeconomics , economics
We use a combination of first‐principles density functional theory and non‐perturbative scattering theory to investigate the effect of point defects on the hole leakage current through ultra thin oxide films. In particular, we consider O vacancies and B interstitial in monoclinic HfO 2 ; five different defects are considered: (1) O vacancy at a three‐ and (2) a four‐coordinated O site located in the HfO 2 region, (3) O vacancy along a Hf–O–Si bond and (4) along a Si–O–Si bond at the Si/HfO 2 interface, and (5) an interstitial Batom in the HfO 2 region. We find that the neutral bulk vacancies and an interface vacancy along theSi–O–Si bond have little impact on the leakage current. On the contrary, an interface vacancy along the Hf–O–Si bridge and an interstitial B atom in the HfO 2 region introduce states in the Si band gap and in the region just below the Si valence band edge thus strongly enhancing the leakage current at a low bias. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)